Water Drops and Cavitation Bubbles

in Microgravity

56th International Astronautical Congress17th October 2005, Fukuoka, Japan

D. Obreschkow, P. Kobel, N. Dorsaz, A. de Bosset,

C. Nicollier, and M. Farhat

About cavitation

Cavitationbubbles

Implosionphenomena

Concernedtechnologies

Damage

Goal

Confined shockwave

Observe all liquid jets

Interaction with spherical free surface

Water Drop

Cavitation Bubble

Here we go !

Part I

Water Drop

Drop Formation & Fixation

Drop Growth

10 mm

Drop Oscillations

1/e damp outtime = 0.7s

Drop-Electrodes Interaction

Negligible interaction

Repulsionby electrodes

Attractionby electrodes

Part II

Cavitation Bubble

It’s really fast !

Close-up

Stability of Drop and Free Surface

Counterjet Geometry

Planar free surface(ground experiment)

Spherical free surface(microgravity experiment)

bubble bubble

[Robinson et al. 01]

Free Surface

High pressure

Numerical Simulation

Shockwave-Nuclei Interaction

0.0ms 0.08ms 0.16ms

Shockwave Energy

Potential Energy

Evidence for “Hairjets”

= 0.95 (± 0.1)

Implosion Process

Modified Rayleigh-Plesset equation (empty bubble):

Rb(t)

Rd(t)

Conclusions

Direct Observation of Jet-Pair

Counterjet Geometry Change

Shockwave Confinement

Shockwave Energy Measurement

Stable Water Drop Formation

Damp Out Oscillations

FOLLOW-UP IDEAS: • Polarized Light (Schlieren) !• Higher time/space resolution• Smaller area of support

FLASH & SPLASH !

Appendix

Flight Maneuver

Global Evolution

Bubble inside extended volume on ground

Rayleigh-Plesset equation (empty bubble)